Figuring out the culprit for your tiredness, bloat, breakout, what-have-you, is tricky. It’s a struggle celebrity chef and restaurateur Seamus Mullen knows all too well. For years, he suffered from aches, pains, and fatigue (often extreme) caused by his rheumatoid arthritis. At a recent event for The Well+Good Cookbook hosted by Moet Hennessy, Mullen revealed the surprising simple way he got to the bottom of his complex health issues. “I took a photo of everything I ate or drank,” he says. “Anytime I was about to put something in my mouth, I took a photo.”

It doesn’t get any easier than snapping a photo in the moment. Upon reviewing the photos at the end of each day and again every morning, Mullen journaled about how he was feeling. “I could look back through my food journal and see what I was eating on the days my body felt great, and the days when my body didn’t feel so great,” he says.

Mullen emphasizes that his method and objectives for keeping a photo food diary differ in that many food diaries or apps focus on counting calories or carbs. His photos and journal entries aren’t about counting macros, but rather about simply looking at what he was putting into his body and how it made him feel.

Blood tests can help pinpoint specific food allergies and at-home gut tests can reveal sensitivities, but Mullen’s method could serve as a great starting point—and also serve as insight for your doctor. And besides, chances are, you’re already photographing your food at least some of the time, right? And they say a picture is worth a thousand words.

Speaking of taking photos of food, here’s why avocado toast became a thing. And if you’re especially into food porn, follow @wellandgoodeats for the prettiest photos on IG.